Department of Chemistry, University of Manchester, Manchester, UK.
National Graphene Institute, University of Manchester, Manchester, UK.
Nat Commun. 2021 May 25;12(1):3092. doi: 10.1038/s41467-021-23325-3.
Membrane-based applications such as osmotic power generation, desalination and molecular separation would benefit from decreasing water friction in nanoscale channels. However, mechanisms that allow fast water flows are not fully understood yet. Here we report angstrom-scale capillaries made from atomically flat crystals and study the effect of confining walls' material on water friction. A massive difference is observed between channels made from isostructural graphite and hexagonal boron nitride, which is attributed to different electrostatic and chemical interactions at the solid-liquid interface. Using precision microgravimetry and ion streaming measurements, we evaluate the slip length, a measure of water friction, and investigate its possible links with electrical conductivity, wettability, surface charge and polarity of the confining walls. We also show that water friction can be controlled using hybrid capillaries with different slip lengths at opposing walls. The reported advances extend nanofluidics' toolkit for designing smart membranes and mimicking manifold machinery of biological channels.
基于膜的应用，如渗透发电、海水淡化和分子分离，将受益于减少纳米通道中的水摩擦。然而，允许快速水流的机制尚未完全理解。在这里，我们报告了由原子级平坦晶体制成的埃级毛细管道，并研究了约束壁材料对水摩擦的影响。从结构相同的石墨和六方氮化硼制成的通道中观察到巨大的差异，这归因于固-液界面处的不同静电和化学相互作用。我们使用精密微量天平测量和离子流测量，评估滑移长度，这是衡量水摩擦的一个指标，并研究其与电导率、润湿性、约束壁的表面电荷和极性的可能联系。我们还表明，可以使用具有不同滑移长度的混合毛细管道来控制水摩擦。所报道的进展扩展了纳米流体学的工具包，用于设计智能膜和模拟生物通道的多种机械。
